1. Field of the Invention
The present invention relates to a damper mechanism and a damper disk assembly for transmitting torque and absorbing torsion vibrations. More specifically, the present invention relates to a damper mechanism and a damper disk assembly that contain a pair of elastic members functionally provided in series with each other.
2. Background Information
A damper mechanism is typically used in a power transmission system for absorbing and attenuating torsional vibrations as well as transmitting torque. The damper mechanism is typically equipped with a first rotating member, a second rotating member, and torsion springs or elastic members. The elastic members or torsion springs are placed between the two rotating members, and are compressed when the two rotating members rotate relative to each other. A typical torsion spring is made of a coil spring. A typical elastic member can be made of rubber or plastic. A damper mechanism can be built into such devices as a clutch disk assembly, a flywheel assembly, and a lockup device of a torque converter.
A coil spring used in a damper mechanism is typically an arc type that extends in an elongated arc shape along the rotational direction of the damper mechanism in order to achieve a low rigidity and a wide torsion angle of the damper mechanism. However, an arc type coil spring tends to have a problem in that the middle section of the coil spring moves outward in the radial direction during the compression cycle due to the radially outward component force and thus, rubs against other components. This increases the friction resistance and hampers the vibration absorption function of the damper mechanism.
As shown in Japanese Patent Application Publication H1-46746, which is hereby incorporated by reference, a solution for such a problem using a structure of having a pair of coil springs instead of an arc type coil spring is well known. An intermediate float member is placed between the ends of the pair of coil springs in the rotational direction.
The damper mechanism disclosed by H1-46746 has a problem in that although it provides a certain level of low rigidity characteristics due to a pair of coil springs functionally provided in series with each other in the rotational direction, it is difficult to achieve a multi-stage characteristic while realizing a low torsion rigidity at least in the low torque region. Thus, further improvement of the characteristics is hindered with the conventional structures.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved damper mechanism and damper disk assembly. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.